C AND N STABLE ISOTOPE SIGNATURES REVEAL CONSTRAINTS TO NUTRITIONAL MODES IN ORCHIDS FROM THE MEDITERRANEAN AND MACARONESIA
C AND N STABLE ISOTOPE SIGNATURES REVEAL CONSTRAINTS TO NUTRITIONAL MODES IN ORCHIDS FROM THE MEDITERRANEAN AND MACARONESIA
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DOI：
10.3732/ajb.0900354
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发表时间：
2010-06-01
影响因子：
3
通讯作者：
Gebauer, Gerhard
中科院分区：
文献类型：
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作者：
Liebel, Heiko T.;Bidartondo, Martin I.;Gebauer, Gerhard
我们比较了兰花的营养模式和栖息地（例如，自养的，部分或完全菌异养的），产于地中海地区和Macaronesia的邻近岛屿。我们假设生态因素（例如，相对的光照、周围的植被）决定了兰花的营养模式，从而限制了兰花的分布。从地中海和Macaronesia的20个地点收集了14属35种兰花样品，以测试从黑暗的森林到开阔地的栖息地。通过分子生物学分析鉴定了菌根真菌，并应用稳定同位素分析检测了真菌共生体是否吸收了有机养分。我们的研究结果表明，兰花与部分或全部的真菌异养的调查物种中被发现只在Neottieae蓬勃发展的光有限的森林。Neottioid兰花在Macaronesia中缺失，可能是因为真菌异养受到缺乏合适的外生菌根真菌的限制。此外，大多数成年兰花的开放栖息地在地中海和Macaronesia显示弱或没有N增益从真菌和没有C增益通过mycoheterotrophy。相反，这些物种的同位素特征表明，净植物到真菌的碳转移。
We compared the nutritional modes and habitats of orchids (e.g., autotrophic, partially or fully mycoheterotrophic) of the Mediterranean region and adjacent islands of Macaronesia. We hypothesized that ecological factors (e.g., relative light availability, surrounding vegetation) determine the nutritional modes of orchids and thus impose restrictions upon orchid distribution. Covering habitats from dark forests to open sites, orchid samples of 35 species from 14 genera were collected from 20 locations in the Mediterranean and Macaronesia to test for mycoheterotrophy. Mycorrhizal fungi were identified via molecular analyses, and stable isotope analyses were applied to test whether organic nutrients are gained from the fungal associates. Our results show that orchids with partial or full mycoheterotrophy among the investigated species are found exclusively in Neottieae thriving in light-limited forests. Neottioid orchids are missing in Macaronesia, possibly because mycoheterotrophy is constrained by the lack of suitable ectomycorrhizal fungi. Furthermore, most adult orchids of open habitats in the Mediterranean and Macaronesia show weak or no N gains from fungi and no C gain through mycoheterotrophy. Instead isotope signatures of some of these species indicate net plant-to-fungus C transfer.